Cholesterol and sphingomyelin syntheses are regulated independently in cultured human intestinal cells, CaCo-2: role of membrane cholesterol and sphingomyelin content.
There is a presumed association between cellular cholesterol and sphingomyelin metabolism. To study this relationship in the intestine, the activity of the rate controlling enzyme of sphingolipid synthesis, serine palmitoyltransferase (SPT), and the biosynthesis of long-chain bases were characterize...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Elsevier
1993-12-01
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| Series: | Journal of Lipid Research |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S0022227520353566 |
| _version_ | 1818725570934996992 |
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| author | Heshun Chen Ella Born Satya N. Mathur F. Jeffrey Field |
| author_facet | Heshun Chen Ella Born Satya N. Mathur F. Jeffrey Field |
| author_sort | Heshun Chen |
| collection | DOAJ |
| description | There is a presumed association between cellular cholesterol and sphingomyelin metabolism. To study this relationship in the intestine, the activity of the rate controlling enzyme of sphingolipid synthesis, serine palmitoyltransferase (SPT), and the biosynthesis of long-chain bases were characterized in cultured human intestinal cells, CaCo-2. Cells were then incubated with substances known to alter cholesterol biosynthesis, and the effect of these mediators on SPT activity and long-chain base synthesis was determined and compared with their effects on HMG-CoA reductase activity and cholesterol synthesis. The polar sterol, 25-hydroxycholesterol, the squalene epoxide inhibitor, U18666A, and the inhibitor of HMG-CoA reductase, lovastatin, all significantly inhibited the synthesis of cholesterol without altering either SPT activity or long-chain base synthesis. Mevalonate, which increased cholesterol production 3-fold, also had no affect on SPT activity or sphingoid base synthesis. Serine, which significantly increased the synthesis of long-chain bases, did not alter cholesterol biosynthesis. Moreover, the suicide inhibitors of SPT, beta-chloroalanine and cycloserine, did not alter cholesterol synthesis while markedly decreasing long chain base synthesis. Cells were incubated with palmitic, oleic, linoleic, and eicosapentaenoic acids. Only palmitic acid, the preferred substrate for SPT, increased the production of long-chain bases. Both palmitic and oleic acids, however, increased the synthesis of cholesterol. Cells enriched in sphingomyelin had higher rates of synthesis of both cholesterol and long-chain bases compared to their controls. In contrast, cholesterol and long-chain base syntheses were significantly decreased in cells enriched in cholesterol. Control cells incubated with phospholipid liposomes alone had higher rates of synthesis of both lipids. The results suggest that SPT and HMG-CoA reductase activities and cholesterol and long-chain base syntheses are regulated independently when the synthesis of either cholesterol or sphingomyelin is altered acutely. However, when membrane cholesterol or sphingomyelin mass are altered, parallel changes occur in the rates of synthesis of these two lipids. SPT activity in human small intestinal mucosa is also documented. |
| first_indexed | 2024-12-17T21:44:25Z |
| format | Article |
| id | doaj.art-e0c27ddd4ed04a2caab5e87cc6ad30f6 |
| institution | Directory Open Access Journal |
| issn | 0022-2275 |
| language | English |
| last_indexed | 2024-12-17T21:44:25Z |
| publishDate | 1993-12-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Journal of Lipid Research |
| spelling | doaj.art-e0c27ddd4ed04a2caab5e87cc6ad30f62022-12-21T21:31:31ZengElsevierJournal of Lipid Research0022-22751993-12-01341221592167Cholesterol and sphingomyelin syntheses are regulated independently in cultured human intestinal cells, CaCo-2: role of membrane cholesterol and sphingomyelin content.Heshun Chen0Ella Born1Satya N. Mathur2F. Jeffrey Field3Department of Internal Medicine, University of Iowa and the Veterans Administration, Iowa City, IA 52242.Department of Internal Medicine, University of Iowa and the Veterans Administration, Iowa City, IA 52242.Department of Internal Medicine, University of Iowa and the Veterans Administration, Iowa City, IA 52242.To whom correspondence should be addressed.; Department of Internal Medicine, University of Iowa and the Veterans Administration, Iowa City, IA 52242.There is a presumed association between cellular cholesterol and sphingomyelin metabolism. To study this relationship in the intestine, the activity of the rate controlling enzyme of sphingolipid synthesis, serine palmitoyltransferase (SPT), and the biosynthesis of long-chain bases were characterized in cultured human intestinal cells, CaCo-2. Cells were then incubated with substances known to alter cholesterol biosynthesis, and the effect of these mediators on SPT activity and long-chain base synthesis was determined and compared with their effects on HMG-CoA reductase activity and cholesterol synthesis. The polar sterol, 25-hydroxycholesterol, the squalene epoxide inhibitor, U18666A, and the inhibitor of HMG-CoA reductase, lovastatin, all significantly inhibited the synthesis of cholesterol without altering either SPT activity or long-chain base synthesis. Mevalonate, which increased cholesterol production 3-fold, also had no affect on SPT activity or sphingoid base synthesis. Serine, which significantly increased the synthesis of long-chain bases, did not alter cholesterol biosynthesis. Moreover, the suicide inhibitors of SPT, beta-chloroalanine and cycloserine, did not alter cholesterol synthesis while markedly decreasing long chain base synthesis. Cells were incubated with palmitic, oleic, linoleic, and eicosapentaenoic acids. Only palmitic acid, the preferred substrate for SPT, increased the production of long-chain bases. Both palmitic and oleic acids, however, increased the synthesis of cholesterol. Cells enriched in sphingomyelin had higher rates of synthesis of both cholesterol and long-chain bases compared to their controls. In contrast, cholesterol and long-chain base syntheses were significantly decreased in cells enriched in cholesterol. Control cells incubated with phospholipid liposomes alone had higher rates of synthesis of both lipids. The results suggest that SPT and HMG-CoA reductase activities and cholesterol and long-chain base syntheses are regulated independently when the synthesis of either cholesterol or sphingomyelin is altered acutely. However, when membrane cholesterol or sphingomyelin mass are altered, parallel changes occur in the rates of synthesis of these two lipids. SPT activity in human small intestinal mucosa is also documented.http://www.sciencedirect.com/science/article/pii/S0022227520353566sphingolipidsserine palmitoyl-CoA transferaseHMG-CoA reductase |
| spellingShingle | Heshun Chen Ella Born Satya N. Mathur F. Jeffrey Field Cholesterol and sphingomyelin syntheses are regulated independently in cultured human intestinal cells, CaCo-2: role of membrane cholesterol and sphingomyelin content. Journal of Lipid Research sphingolipids serine palmitoyl-CoA transferase HMG-CoA reductase |
| title | Cholesterol and sphingomyelin syntheses are regulated independently in cultured human intestinal cells, CaCo-2: role of membrane cholesterol and sphingomyelin content. |
| title_full | Cholesterol and sphingomyelin syntheses are regulated independently in cultured human intestinal cells, CaCo-2: role of membrane cholesterol and sphingomyelin content. |
| title_fullStr | Cholesterol and sphingomyelin syntheses are regulated independently in cultured human intestinal cells, CaCo-2: role of membrane cholesterol and sphingomyelin content. |
| title_full_unstemmed | Cholesterol and sphingomyelin syntheses are regulated independently in cultured human intestinal cells, CaCo-2: role of membrane cholesterol and sphingomyelin content. |
| title_short | Cholesterol and sphingomyelin syntheses are regulated independently in cultured human intestinal cells, CaCo-2: role of membrane cholesterol and sphingomyelin content. |
| title_sort | cholesterol and sphingomyelin syntheses are regulated independently in cultured human intestinal cells caco 2 role of membrane cholesterol and sphingomyelin content |
| topic | sphingolipids serine palmitoyl-CoA transferase HMG-CoA reductase |
| url | http://www.sciencedirect.com/science/article/pii/S0022227520353566 |
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